[the OlLine Rebel]

??
The poem was called “the Defense of Ft. McHenry”, and is set in the so-called War of 1812 (British War).
So no, not quite.

[Tucker39]

Right. My bad......sorta. Key was writing about the defense of Ft. McHenry, which happened in the 1812 War. But that doesn’t change the fact that the Hessians were hired mercenaries, i.e., “hirelings”, which Key alluded to historically in his poem.